The compromise of fuelling an F1 car.

[ajdavison2]

After watching the GP this weekend, the whole Hamilton having to save fuel issue got me thinking. Obviously the teams want to carry as little fuel as possible to avoid carrying excess weight around the track. My query was that would there be a greater benefit in fuelling a driver to enable him to drive at full pace for the full race, rather than short fuelling and forcing him to go into fuel saving mode at some stage? I'm no engineer so I don't have any idea about the relative pros and cons of such a strategy, for example would the extra weight negate the ability to drive flat out?

Alex.

[beelsebob]

Absolutely there is a compromise here – ultimately you get lap time due to weight & added tyre wear traded off against lap time due to having to run the engine lean. At each circuit teams will calculate (and observe from practice session data) predicted fuel usage and lap time penalty for carrying fuel, they'll make a model, and they'll chose a minimum on the curve to suit them. Of course various things in the race can also affect fuel usage, like betting on safety cars, being stuck behind people etc.

[747heavy]

........................ not the rigth place - sorry

[dren]

I agree with that. They probably hoped for a safety car with the wet conditions early on.

[Richard]

Or perhaps they hoped for wetter conditions (hence slower speeds).

They did admit that Button had 1kg more fuel. How much is that worth? 1 lap?

[SiLo]

It is interesting, and also a shame because I wanted to see what Hamilton could really do.
Surely letting them race as hard as they can all the way to the flag is how things should be?

[hardingfv32]

Are not these types of gambles the stuff of the second tier teams?

Brian

[PlatinumZealot]

Or perhaps they hoped for wetter conditions (hence slower speeds).

They did admit that Button had 1kg more fuel. How much is that worth? 1 lap?

At an average of about 2.6kg per lap. that's about a third of a lap.

Hamilton had to start saving fuel from lap 31. More than likely Button would start saving fuel around the same time or a little later, Maybe lap 32.

[Muulka]

mcLAren said that they had no idea what the fuel economy of the car was going to be in the race- it seems that their quali pace was far slower than the car was capable of, an they were surprised by the lap times- they guessed, but alas, they were wrong.

[beelsebob]

Or perhaps they hoped for wetter conditions (hence slower speeds).

They did admit that Button had 1kg more fuel. How much is that worth? 1 lap?

At an average of about 2.6kg per lap. that's about a third of a lap.

Hamilton had to start saving fuel from lap 31. More than likely Button would start saving fuel around the same time or a little later, Maybe lap 32.

Something's off – you cite 2.6Kg per lap, someone in the MP4-26 thread cited 0.3 seconds per Kg, that implies a speedup of nearly a second a lap – doesn't sound doable. Which figure is out?

[747heavy]

........................ not the rigth place - sorry

[ajdavison2]

Plus Button had a slower first stint, hence using less fuel than Hamilton

[strad]

Puts me in mind of Jim Clark and Chapman. Colin ran Jimmy out of gas tgrying to save the weight of I believe 1 gallon of gas.

[marcush.]

the estimate of 2.6kg/lap is reasonable - IMHO, I would probably say it´s a bit higher under full dry conditions. ~160kg/52 laps = ~3kg/lap, it´s a quick and dirty calc, but as an order of magnitude I would say it´s reasonable.

the 0.3 sec/kg seems way too high IMHO, it´s closer to 0.3sec/10kg or 0.03sec/kg.
You find this value mentioned in the McLaren paper I posted and it was mentioned often during the KERS debate in 2009.
Again, it´s just an estimate, it´s not set in stone, and will depend on the track. On a track with many acceleration/braking sections (Monaco etc.) it will be higher then on a flowing track with higher, more constant average speed.

Sorry, but I don´t think that they underfueld him by just 1kg, if this is the case,
then Button would have had the same problem.
Due to his pitstop mishap, we will never know.
I would say (but that´s just my opinion) they where ~10kg short of fuel.

there you go ...so it´s 3tenths of car speed won at the xpense of having to cruise for 20 laps.
counting it up that would amount to 9 seconds less elapsed time till they had to
ask him to nurse the engine...there are better ways to find 9 seconds in race elapsed time-for example a fresh set of soft tyres or an excellent pit call on changeable conditions.
In effect that´s only shifting the car potential from the end of the race bringing it a bit forward.

[Formula None]

Semi related, but I bet the average lollipop man wishes he still had 8 seconds to check if all the wheelnuts were secured.